The invention relates to a mowing machine provided with a frame and with a plurality of mowing means arranged side by side in a row, which are supported by the frame, which mowing means are rotatable about upwardly extending axes of rotation during operation and which are each connected to a pulley, whilst a driving belt is passed over said pulleys connected to the mowing means, said driving belt also being passed over a pulley arranged near one end of the row of mowing means, which pulley can be driven from a driving source driving the mowing machine during operation.
Such mowing machines are generally known, e.g. from European Patent Applications Nos. 0 206 965 and 0 404 213. The drivable pulley is thereby generally driven from the power take-off shaft of a tractor moving the mowing machine during operation. The driving belt is furthermore passed along the similarly constructed pulleys connected to the mowing means, in such a manner that the belt surrounds each of the various pulleys connected to the mowing means through at least substantially the same circumferential angle.
It is noted that from GB-A-2056836 a device is known wherein three mowing means are driven from a drivable pulley by means of a V-belt. The mowing means located nearest the drivable pulley is connected to a pulley which has a flat cylindrical outer circumference and which co-operates with the flat rear side of the V-belt. The pulleys connected to the other mowing means have the usual V-shaped groove for co-operation with the V-belt in the usual manner. In order to try to prevent the occurrence of slip between the flat rear side of the V-belt and the pulley co-operating with said flat rear side said pulley is surrounded by the V-belt through a large circumferential angle, whilst at the same time large tensions are set up in the V-belt near said pulley. This may lead to undesirably high tensions in the V-belt.
FR-A-1.549.969 relates to a mowing device wherein use is made of a toothed belt for driving said device, the toothed surface of said belt co-operates with toothed pulleys, which are connected to part of the mowing means, whilst the opposite smooth surface of the belt co-operates with flat pulleys, which are connected to further mowing means. FR-A-1.549.969 thereby mentions that, with regard to the angle through which the belt extends over a pulley, account is taken for the fact whether the belt co-operates with a smooth or with a toothed pulley. However, said publication does not provide any indication with regard to the problem underlying the present invention and/or with regard to the solution of said problem.
Furthermore, with mowing machines equipped with a belt transmission the pulleys are generally fixedly connected to the driving shafts of the mowing means. During operation of such mowing machines it may occur that a mowing means is blocked, e.g. by some obstacle or other, so that both the mowing means and the pulley secured thereto via the driving shaft will come to a stop. As a result of this the driving belt will start to slip with respect to the pulley. If said blocking of a mowing means is not immediately noticed by the operator of the mowing machine, it may happen that the driving belt will slip with respect to the blocked pulley for some time, as a result of which the temperature of the pulley may strongly increase. When after some time the operator notices that a mowing means is blocked and the operator stops the drive of the mowing machine, the belt will come to a stop and a part of the belt, which is stationary at that moment, will be in contact with a strongly heated part of the blocked pulley. This may seriously affect the material of the driving belt and cause a local weakening of the driving belt, which may eventually result in the driving belt breaking prematurely.